1. Field of the Invention
The present invention relates to an image forming apparatus which forms an image on a sheet.
2. Description of the Related Art
A sheet cassette in an image forming apparatus stores sheets on which images are to be formed. The image forming apparatus feeds the sheets one by one from the sheet cassette to an image forming unit, and the image forming unit forms images on the sheets.
Japanese Patent Application Laid-Open No. 2006-182463 discusses a sensor disposed in the sheet cassette, which detects whether a sheet or sheets are present in the sheet cassette. The sensor detects whether the sheets in the sheet cassette have run out while the sheets are sequentially fed from the sheet cassette. The image forming apparatus temporarily stops an image forming operation based on detection by the sensor, and notifies a user that the sheets in the sheet cassette have run out.
Japanese Patent Application Laid-Open No. 2006-182463 discusses disposing a dedicated sensor for detecting whether there is a sheet in the sheet cassette. Further, a dedicated space is necessary for arranging the sensor in the apparatus. It is thus desirable to commonly use the sensor so that cost can be reduced and the apparatus can be downsized.